Anode support



Aug. 20, 1957 w. w. \QNATROUS, JR

ANODE SUPPORT Filed July 14, 1955 FIG.|

FIG. 2

WARD 'W. WATROUS, JR.

INYENTOR ATTORNEY atent 12,03,775 Patented Aug. 20, 1957 ANODE SUPPORT Ward W. Watrous, J12, Chatharn, N. J., assignor to Chatham Electronics, Division of Gera Corporation, Livingston, N. 3., a corporation of New Jersey Application .inly 14, 1955, Serial No. 522,654 4 Claims. (Cl. 313-219) This invention relates to an anode support for a gaseous discharge device and has particular reference to a structure which will withstand high voltages, conduct high currents, and conduct a large amount of heat.

It has been customary to support the anode electrode of gaseous discharge devices on a lead-in conductor at one end of an envelope which encloses all the electrodes and retains the ionizable gas. Such a simple support will withstand very high voltages, but on certain types of discharge devices it is necessary to shield the anode with a conductive shield to eliminate undesirable discharges not controlled by a control electrode. When a shield is used around the anode it becomes difiicult to isolate the anode conductor at its upper extremity so that discharges will not occur between the unshielded lead-in portion and the upper part of the shield. In addition, for all discharge devices passing high currents, there is a serious problem of heat disposal and the anode lead-in conductor should contain a reasonably large cross section of heat conductive material. The present design fulfills all the above requirements and the structure is so designed as to give complete anode shielding in the space where electrical discharges may occur between the cathode and the anode and in addition the spacing is so proportioned that gaseous discharges cannot occur due to ionized gas molecules.

One of the objects of this invention is to provide an improved anode support for gaseous discharge devices which avoids one or more of the disadvantages and limitations of prior art arrangements.

Another object of the invention is to provide an anode support which will withstand high voltages without pro ducing undesired electrical discharges.

Another object of the invention is to facilitate the flow of heat from an anode electrode within a gaseous discharge device to cooling vanes exterior of the device or to a tank which contains a liquid for cooling.

Another object of the invention is to facilitate the assembly of high voltage anode structures which are insulated by a portion of the glass voltage envelope.

The invention includes an anode supported by a cylindrical conductor which is formed with an annular groove extending around its cylindrical surface some distance from the anode. The upper portion of the anode shield is secured to a cylindrical shield coaxially aligned with the cylindrical conductor and spaced from it by a distance which is considerably less than the mean free path which is necessary for causing gas ionization. The upper end of the cylindrical shield is formed with a rolled edge which fits into the annular groove but is spaced from it by a small distance. A portion of the glass envelope surrounds the upper end of the cylindrical shield and a portion of the upper end of the anode structure by a spacing which is small enough to prevent ionization.

For a better understanding of the present invention, together with other and further objects thereof, reference is made to the following description taken in connection with the accompanying drawings.

Fig. 1 is a cross sectional view showing the upper portion of a gaseous discharge device and including the anode and a portion of the anode shield.

Fig. 2 is a cross sectional view of the anode structure taken along line 2-2 of Fig. 1.

Fig. 3 is a cross sectional view of an anode structure similar to Fig. 1 but showing an alternate design.

Referring now to the drawings, the gaseous discharge device includes a glass envelope 10 which is sealed from the atmosphere and contains gas at a reduced pressure. The envelope also contains a cathode, a control electrode, and a base which includes lead-in conductors for connecting these electrodes to an external circuit. The above components are not shown in the drawing since the invention relates entirely to the anode structure.

An anode 11 is mounted within the envelope and is surrounded by a closely fitting shield 12. The anode is supported by a cylindrical conductor 13 which is joined to the upper anode face and extends in general axial alignment with the envelope through the upper portion thereof. The cylindrical conductor of Fig. 1 is made in two parts, a lower part 13 which holds the anode and an upper part 14 which extends into the space exterior to the envelope. The two parts are joined by a screw thread 315 and near this threaded portion an annular groove 16 is formed in the outer surface of the cylinder. Both parts of the cylindrical conductor are designed to conduct heat as Well as electrical currents and a series of heat dissipating vanes 17 may be mounted at the outer extremity of cylinder 14 for cooling purposes. A nut and bolt 18 are secured to the upper end of conductor 14 for attaching to a flexible circuit conductor.

The anode shield 12 is joined to a cylindricalshield 2-0 which surrounds cylinder 13 and is closely spaced from it. The upper end of this shield is formed with a rolled edge 21 which is turned inwardly to form a ring shaped extremity. The exterior surface of this ring 21' fits into the groove 16 but does not make contact with it anywhere, being equidistant from the grooved surface at all adjacentpoints.

The glass envelope 10 is formed with a ring seal 22 which joins it to a short glass cylinder 23 extending both intoand out of the space enclosed by the main portion of the envelope 10. The upper end of glass cylinder 23 is joined by a glass-to-metal seal 24 to a flat ring shaped conductor 25, the upper end of which is welded to conductor 14.

At the inside extremity of glass cylinder 23 a similar glass-to-metal seal 26 is formed with a second flat ring 27 which is welded to the cylindrical shield 20. It will be obvious that the upper weld between ring 25 and cylinder 14 must be gas-tight while the lower weld between ring 27 and shield 2d need not be gas-tight but the parts must be sufiiciently close so that no gas discharge may form between their surfaces.

The central part of shield 12 is formed with a curved surface 28 and the adjacent portion of cylindrical conductor 1.3 is formed with a similar curved surface 30. The absence of sharp edges and points that otherwise might be formed in the structure eliminates .high intensity electric fields and thereby reduces the probability of undesirable electrical discharges. t will be evident that the close spacing between shield 20 and cylindrical conductor 13 eliminates the possibility of gas ionization between these two conductors even though their voltage diiference may be as high as 50,000 volts and the curved over portion 21 which is fitted into the annular groove 16 performs a like purpose.

One of the main advantages of resides in the fact that there is a conductive path from the anode 11 the present invention direct and ample heat to the cooling fins 17.

If it is desired to increase the heat conductivity, the

walls of cylinders 13 and 14 may be made much thicker and the joint 15 may be eliminated.

The alternate design shown in Fig. 3 contains such a solid heat conducting path between the anode 11 and the fins .17. In this design'the anode shield 12 and the envelope have the same configuration as in the previously described support. Also the cylindrical shield 20 and its turned-over portion 21 are formed in the same manner. However, the cylindrical support 32 is solid and has .an upper portion 32A which is smaller in diameter than the lower portion which is joined to the anode. Near the top of support 32A a cylinder 25 of a glass sealing alloy is brazed to the support to form a gas-tight seal and the uppor portion of the glass envelope 23 is sealed to the upper portion of the cylinder .25. Cooling vanes 17 .are employed as before but in this design they must be brazed or afl'ixed to the top portion of support 32A after the seal has been completed.

The alternate design shown in Fig. 3 .includes the same insulating .characteristics as the design shown in Fig. 1 since there are no sharp corners and no long distances greater :than the mean :free path which can cause ionization and support a permanent'discharge.

It should be noted that the space between the glass cylinder 23 and conductors 20 and 14 is also smaller than the mean free path and therefore no gas ionization may be generated in this space by means of the electric field which exists between the anode support and any one of the shields.

From the above description it will be evident that an anode structure .has been provided which is completely shielded to eliminate all undesirable discharges between the anode and any other electrode within the glass envelope and still provides a structural means for eliminating gas discharges between parts of the shield and the lead-in conductor.

While there .have been described and illustrated specific embodiments of the invention, it will be obvious that various changes and modifications may be made therein without departing from the field of the invention which should be limited only by the scope of the appended claims.

I claim:

1. An electrode support in a gaseous discharge device having gas at a reduced pressure 'within an envelope comprising, a cylindrical lead-in conductor sealed in the envelope and secured to an anode therein, said conductor formed with an annular groove extending around its surface, a conductive cylindrical shield within the envelope surrounding a portion of the lead-in conductor in axial alignment therewith and closely spaced therefrom,

l a non-conductive cylindrical portion of said envelope closely surrounding said shield, and a toroidal end portion of said shield closely mounted adjacent to said annular groove, said closely mounted elements spaced a distance therebetween which is less than one-fourth the mean free path of electrons in the gas.

2. An electrode support in a gaseous discharge device having a gas at a reduced pressure within an envelope comprising, a lead-in conductor sealed in the envelope and secured to an anode therein, said conductor formed with an annular groove extending around its surface, and a conductive shield surrounding a portion of the lead: in conductor within the envelope, the end of said shield formed with a toroid having a circular cross section, said toroid equally spaced from the surface of said annular groove, said conductor and said shield spaced a distance therebetween which is less than one-fourth the mean free path of electrons in the gas.

3. An electrode support in a gaseous discharge device having a gas at a reduced pressure within an envelope comprising, a lead-in conductor sealed in the envelope and secured to an electrode therein, saidconductor formed with an annular groove extending around its surface, and a conductive shield surrounding a portion of the lead-in conductor within the envelope and spaced therefrom :a distance which is small in comparison to the mean free path of electrons in the gas, the end of said shield formed with a rolled edge adjacent to the annular groove and closely spaced therefrom.

4. An electrode support in a gaseous discharge device having a gas at a reduced pressure within an envelope comprising, a cylindrical lead-in conductor sealed in the envelope and secured to an electrode therein, said conductor formed with an annular groove extending around its surface, a conductive cylindrical shield within the envelope surrounding a portion of the lead-in conductor in axial alignment therewith and closely spaced therefrom, a non-conductive cylindrical portion of said envelope closely surrounding said shield, and arolled-over end portion of said shield closely mounted adjacent to said annular groove, said closely mounted elements having a space therebetween which is small in comparison .to the mean free path of electrons in the gas.

References Cited in the file of this patent 

